ONCEMRK is a multicenter, double-blind, randomized, active comparator-controlled Phase 3 trial. The study is evaluating the efficacy and safety of raltegravir 1200mg (given as 2 x 600mg) once daily compared to Isentress 400mg twice daily each in combination therapy with Truvada in previously untreated HIV-1 infected adults for a total of 96 weeks. The primary endpoint is the proportion of patients achieving HIV RNA <40 copies/mL at Week 48.

Study results showed that raltegravir 1200mg once daily was statistically non-inferior to the approved Isentress 400mg twice daily formulation, each in combination therapy with Truvada. The study met its primary endpoint, as assessed by the proportion of patients achieving HIV-1 RNA <40 copies/mL at Week 48. Merck plans to present detailed study results at an upcoming scientific conference and submit applications for licensure to the Food and Drug Administration (FDA) later this year.

Isentress, an integrase inhibitor, is currently indicated as twice daily administration in combination with other antiretroviral agents for the treatment of HIV-1 infection in patients ≥4 weeks old. The investigational once daily formulation is not interchangeable with the currently marketed 400mg tablet.